WDS stopped working in 21.02, looking for bug in netifd

[Daniel Haid]

Felix, I took the last openwrt snapshot and compiled netifd from master 
with your patch applied and installed it.

Result:
After boot wlan0.sta1 was DOWN.
After "/etc/init.d/network restart" it was UP and the connection worked!
After another "/etc/init.d/network restart" it was DOWN again.
After reboot it was UP again and working.
After "/etc/init.d/network restart" it was DOWN again.

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D.H.